In the light soils stable-manure wastes too rapidly because, for one reason, at the extremes of high temperature, oxidation and decay proceed with great rapidity, and the volatile portions of the fertilizer are used up faster than the plant can appropriate them, so that not only are they wasted during the early periods of growth, but they are wanting at a later period when their absence may prove the failure of a crop. B. The ingredients and qualities which make peat _a direct fertilizer_ next come under discussion. We shall notice: _The organic matters including nitrogen (ammonia and nitric acid)_ (I): _The inorganic or mineral ingredients_ (II): _Peculiarities in the decay of Peat_ (III), _and_ _Institute a comparison between peat and stable manure_ (IV). I.--Under this division we have to consider: 1. _The organic matters as direct food to plants._ Thirty years ago, when Chemistry and Vegetable Physiology began to be applied to Agriculture, the opinion was firmly held among scientific men, that the organic parts of humus--by which we understand decayed vegetable matter, such as is found to a greater or less extent in all good soils, and _abounds_ in many fertile ones, such as constitutes the leaf-mold of forests, such as is produced in the fermenting of stable manure, and that forms the principal part of swamp-muck and peat,--are the true nourishment of vegetation, at any rate of the higher orders of plants, those which supply food to man and to domestic animals. In 1840, Liebig, in his celebrated treatise on the "Applications of Chemistry to Agriculture and Physiology," gave as his opinion that these organic bodies do not nourish vegetation except by the products of their decay. He asserted that they cannot enter the plant directly, but that the water, carbonic acid and ammonia resulting from their decay, are the substances actually imbibed by plants, and from these alone is built up the organic or combustible part of vegetation. To this day there is a division of opinion among scientific men on this subject, some adopting the views of Liebig, others maintaining that certain soluble organic matters, viz., crenic and apocrenic acids are proper food of plants. On the one hand it has been abundantly demonstrated that these organic matters are not at all essential to the growth of agricultural plants, and can constitute but a small part of the actual food of vegetation taken in the aggregate. On the other hand, we are acquainted with no satisfactory evidence that the soluble organic matters of the soil and of peat, especially the crenates and apocrenates, are not actually appropriated by, and, so far as they go, are not directly serviceable as food to plants. Be this as it may, practice has abundantly demonstrated the value of humus as an ingredient of the soil, and if not directly, yet indirectly, it furnishes the material out of which plants build up their parts.